1. Field of the Invention
This invention relates to a method of centering in a roundness measuring instrument and a system therefor, and particularly to a method of centering an article to be measured by the roundness measuring instrument and a system therefor.
2. Description of the Related Art
When roundness and the like of an article to be measured are measured by a roundness measuring instrument, after centering of the article to be measured is carried out, a detector of the roundness measuring instrument is abutted against the article to be measured and the article to be measured is rotated to measure the peripheral surface of the article to be measured, thereby measuring the roundness of the article to be measured. In this case, the centering of the article to be measured is carried out such that, after the article to be measured is rested on a rotatable X-Y table, the detector is abutted against the article to be measured on an X-axis of the X-Y table, the X-Y table is rotated through 180.degree., the X-Y table is moved in a direction of the X-axis by 1/2 of a displacement value of the detector at this time, subsequently, the detector is abutted against the article to be measured on a Y-axis of the X-Y table, the X-Y table is rotated through 180.degree., and the X-Y table is moved in a direction of the Y-axis by 1/2 of the displacement value of the detector at this time, to thereby carry out the centering of the article to be measured.
However, the conventional centering work presents such disadvantages that, since an operator moves the X-Y table by 1/2 of a displacement value of the detector by his own personal skill, it takes time, and further, that, since the centering work is carried out by the personal skill of the operator, a skilled operator for the centering work is required.